How many valence electrons are in Al^3+?

3 valence electrons

Explanation:

Al⁺³ has the electron configuration a of 1s² 2s² 2p⁶ 3s² and 3p¹. Since we are looking for the valence electrons, we are looking for the outer most electrons. These would be in the 3s² and 3p¹ sublevels. Adding the superscripts of these sub levels, we get:

2 + 1 = 3

∴ there are 3 valence electrons in Al⁺³

We can also check this by taking a quick look at the periodic table. We can find aluminum  on the right hand side underneath boron in group 3A. There is something really cool about all the A groups. Notice the number before the A groups? 1A, 2A, 3A...8A. Well, it goes all the way up to 8A. There are exactly 8 valence electrons in an octet a.k.a. "the happy state of elements." In each group, it can be seen that it has a certain number of electrons by its group number. Your alkali have 1 valence electronsall the way to your noble gases which have 8 valence electrons. Seeing that aluminum is in group 3A, we can, thus determine that it has 3 valence electrons.

i believe it is c.) 1575 j.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2